Comparison of the barrier height measurements by the Powell method with the ΦMS measurement results, Journal of Telecommunications and Information Technology, 2005, nr 1

n this work, we have compared the barrier height measurements carried out using the Powell method with the photoelectric effective contact potential difference (&phiMS) measurement results. The photoelectric measurements were performed on the samples that were previously applied in the investigation of the influence of stress on the duration of annealing in nitrogen. This paper shows that the results of barrier height measurement using the Powell method differ significantly from the &phi(MS) measurement results

Effects of stress annealing on the electrical and the optical properties of MOS devices, Journal of Telecommunications and Information Technology, 2005, nr 1

In this paper we show the results of a study of the effects of high-temperature stress annealing in nitrogen on the refraction index of SiO2 layers and electrical properties in metal-oxide-semiconductor (MOS) devices. We have experimentally characterized the dependence of the reduced effective contact potential difference (ECPD), the effective oxide charge density (Neff), and the mid-gap interface trap density (Dit) on the annealing conditions. Subsequently, we have correlated such properties with the dependence of the refraction index and oxide stress on the annealing conditions and silicon dioxide thickness. Also, the dependence of mechanical stress in the Si-SiO2 system on the oxidation and annealing conditions has been experimentally determined. We consider the contributions of the thermal-relaxation and nitrogen incorporation processes in determining changes in the SiO2 layer refractive index and the electrical properties with annealing time. This description is consistent with other annealing studies carried out in argon, where only the thermal relaxation process is present

Long-Term Consequences of Water Pumping on the Ecosystem Functioning of Lake Seksu, Latvia

Cultural eutrophication, the process by which pollution due to human activity speeds up natural eutrophication, is a widespread and consequential issue. Here, we present the 85-year history of a small, initially Lobelia-Isoetes dominated lake. The lake's ecological deterioration was intensified by water pumping station activities when it received replenishment water for more than 10 years from a eutrophic lake through a pipe. In this study, we performed a paleolimnological assessment to determine how the lake's ecosystem functioning changed over time. A multi-proxy (pollen, Cladocera, diatoms, and Chironomidae) approach was applied alongside a quantitative reconstruction of total phosphorus using diatom and hypolimnetic dissolved oxygen with chironomid-based transfer functions. The results of the biotic proxy were supplemented with a geochemical analysis. The results demonstrated significant changes in the lake community's structure, its sediment composition, and its redox conditions due to increased eutrophication, water level fluctuations, and erosion. The additional nutrient load, particularly phosphorus, increased the abundance of planktonic eutrophic-hypereutrophic diatoms, the lake water's transparency decreased, and hypolimnetic anoxia occurred. Cladocera, Chironomidae, and diatoms species indicated a community shift towards eutrophy, while the low trophy species were suppressed or disappeared

ECOLOGICAL CHARACTERISTICS OF GREAT SERTEYA PALEOLAKE BASED ON PALEOECOLOGICAL RESEARCH AT THE SERTEYA II SITE IN WESTERN RUSSIA

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Reconstruction of palaeoecological changes in Lake Łebsko on the basis diatom analysis (the southern Baltic coast, Poland)

This study focuses on diatom assemblages occurring in core Łeb1 of Late-glacial and Holocene deposits from Lake Łebsko, off the southern coast of the Baltic Sea. Diatom-inferred environmental characteristics, e.g., water level, water salinity (conductivity), trophic status and pH, from the Holocene are presented. In the sediments from the early Boreal/early Atlantic period, an increase in the participation of brackish-freshwater species is observed, as well as increased numbers of Chaetoceros spores in the samples. The Atlantic sediments of Lake Łebsko mirror conditions typical of the Littorina Sea phase during the development of the Baltic Sea (from c. 7,500 BP to c. 5,000 BP). However, communities of that period dominated by fresh-brackish water species suggest the relatively low salinity of the waters. The presence of isolated frustules of Terpsinoë americana and other typically marine species, e.g., Mastogloia smithii, and the occurrence of silts with Cardium shell detritus point to the Littorina transgression and the functioning of a lagoon within the area of present-day Lake Łebsko. During Subboreal occurrence, a higher number of brackish-freshwater diatoms corresponds to an increase in the water level of the Baltic Sea (approximately 3,000 14C BP). Changes in diatom community structure imply a close relationship with the climate controlled eustatic rise of ocean level and the consequent Littorina transgression, as with other southern Baltic Sea localities

Effects of stress annealing on the electrical and the optical properties of MOS devices

In this paper we show the results of a study of the effects of high-temperature stress annealing in nitrogen on the refraction index of SiO2 layers and electrical properties in metal-oxide-semiconductor (MOS) devices. We have experimentally characterized the dependence of the reduced effective contact potential difference (ECPD), the effective oxide charge density (Neff), and the mid-gap interface trap density (Dit) on the annealing conditions. Subsequently, we have correlated such properties with the dependence of the refraction index and oxide stress on the annealing conditions and silicon dioxide thickness. Also, the dependence of mechanical stress in the Si-SiO2 system on the oxidation and annealing conditions has been experimentally determined. We consider the contributions of the thermal-relaxation and nitrogen incorporation processes in determining changes in the SiO2 layer refractive index and the electrical properties with annealing time. This description is consistent with other annealing studies carried out in argon, where only the thermal relaxation process is present

Dielectric Function of Native Oxide on Ion-Implanted GaAs

The main aim of the reported investigations is the influence of ion implantation on formation of native oxide layers and their optical spectra. Silicon implanted (100)-oriented GaAs crystalline wafers were used as substrates. The samples have been implanted with $Ne^{+}$, $Al^{+}$, $Ar^{+}$, or $In^{+}$ ions at energies of 100, 120, 150, and 250 keV, respectively. The implantations were carried out at a fluence of $1 \times 10^{16} cm^{-2}$ at 300 K. The refraction index spectral dependence for native oxide was approximated using the Cauchy equations. The dielectric function spectra of the native oxide layers on GaAs implanted with different ions have been obtained by variable angle spectroscopic ellipsometer in the 250-900 nm range using complementary information from the Rutherford backscattering/nuclear reactions measurements. The investigations showed that both real and imaginary parts of the dielectric function increase with mass of the ion species used for implantation

A multidisciplinary study on the palaeoenvironmental history of the Resko Przymorskie Lake spit during the Late Glacial and Holocene (the southern Baltic coast, NW Poland)

The paper presents the results of sedimentological and biostratigraphical analyses from the Resko Przymorskie Lake spit (NW Poland), supported by radiocarbon datings. The study has aimed to recognize the geological structure of the spit and its base and to recognize the palaeoenivronmental changes. Nine sedimentary series composing the Resko Przymorskie Lake spit have been distinguished (I–IX). The oldest sediments are the Vistulian Glaciation till (series I) and fluvioglacial sand and gravel (series II). In the Early Holocene, in the study area there was a river valley (series III) followed by a shallow water basin (series IV), which was replaced by a peat bog (series V). In the Atlantic (7.4 ka cal BP), the water level rose (Littorina transgression) and accumulation of lagoonal sediments started (series VI). Biostratigraphic analysis of deposits in series VI indicates a marine influence. In the Atlantic and Subboreal, the spit moved southwards and fine sand (series VII) was deposited on lagoonal gyttja and silt (series VI). In the western part of the study area, peat accumulated (series VIII), dated at 6.7 ka cal BP (Late Atlantic). The youngest series IX is composed of aeolian fine sand in white dunes that formed in the last 400 years

Comparison of the barrier height measurements by the Powell method with the phi MS measurement results

In this work, we have compared the barrier height measurements carried out using the Powell method with the photoelectric effective contact potential difference (phi MS) measurement results. The photoelectric measurements were performed on the samples that were previously applied in the investigation of the influence of stress on the duration of annealing in nitrogen. This paper shows that the results of barrier height measurement using the Powell method differ significantly from the phi MS measurement results

Optical Analyses of Si and GaAs Semiconductors by Fractional-Derivative-Spectrum Methods

Optical spectra analysis provides a wealth of information on physical properties of various semiconductor materials. Fractional derivative spectrum technique is especially interesting when the limitations of the standard treatment occur. In this paper we present the fractional derivative spectrum method for analysis of the optical spectra for both Si and GaAs. The significant changes in critical point parameters in each treated Si and GaAs samples in comparison to that before treatment have been observed. Our investigation illustrates that fractional derivative spectrum is a very good technique to extract basic information on relevant physical quantities from the observed optical spectra, and it has the advantages of flexibility, directness, and sensitivity, which give possibility to obtain the Van Hove singularities (critical point parameters) efficiently with one consent